Ignition system for fuel burners



April 22, 194-1. J K L K 2,238,890

IGNITION SYSTEM FOR FUEL BURNERS I Filed May 29, 1939 gwumwtoc Patented Apr. 22,1941

IGNITION SYSTEM FOR FUEL BURNERS James K. Clark, New Hartford, N. Y., assignor to The Partlow Corporation, New Hartford, N. Y.

Application May 29, 1939, Serial No. 276,477

Claims.

This invention pertains to ignition systems for fuel burners, and more particularly to electrical control and ignition system for fuel buming furnaces, ovens and the like. The instant application is thus directed to modifications and improvements in the electrical control system for the automatic safety pilot burners shown shut-off means for the fuel in the event of fuel failure; the extinguishment of the pilot flame,

or failure of the electric current supply.

One of the principal objects of the present invention and improvements over said patent is the provision of means for shutting off the fuel supply to the burners in the event of a short circuit of the high tension ignition means of the electrical control system as might occur by an accumulation of soot in the pilot burner, or a ground of the high tension with.

Another object of the invention is to improve and simplify the electrical system, as appears in detail in the specification and claims.

Further objects, details, and advantages of the invention will be more fully set forth in the following specification in conjunction with the accompanying drawing which diagrammatically illustrates electrical control means for a pilot and main burner for a furnace or the like in ac cordance with my invention.

Referring to the diagram, I have shown the electrical control system in accordance with my invention as applied to gas burners for use in furnaces and the like, wherein a main heating burner I and a pilot burner 2, are connected .to a gas supply main 3, by way of branch conduits l and 6 respectively. The gas supply to the main burner is regulated and controlled in the usual manner, a valve 8 in conduit 4 being indicated for the purpose, and similarly a manually operated cut-off valve 1 is shown in conduit 5, for cutting oil. the gas supply to pilot burner 2 when thefurnace is shut down. a The electrical control system, in accordance with my invention, includes electrical ignition means for the pilot burner 2 which is preferably of the type disclosed in detail in my patent and copending application Serial No. 276,475, filed connection thereconcurrently, and includes a jump spark gap 8 which bridges the flame space projecting from the pilot burner nozzle. In addition to the spark gap 8 for the pilot burner, the branch conduits 4 and 5 are provided with electrically operated valves 9 and II! respectively, such as disclosed in my patent, which are opened when energized by the electrical control system.

The electrical system for controlling the burner operation in accordance with the present invention, includes a step-up transformer ii having a primary winding l2 and a secondary winding l3, which supplies a secondary potential suflicient to bridge the jump spark gap 8 of pilot burner 2 during the normal operation of the furnace. Current for opening electrically operated valves 9 and I0 is dependent upon a pair of relays I4 and I5, which in turn are dependent upon the operating conditions of transformer II and is illustrated as a step-down transformer having its primary I1 directly connected with the high potential secondary l3 of transformer II and the circuit of its secondary l8 associated with said relays, as will be set forth.

Transformer H is adapted to be supplied with alternating current by a usual source of supply I9, from a. switch 20, by conductor 2|, to end 22 of primary winding l2, winding l2 of transformer ll, thence from end 23 of winding l2, by conductor 24, through operating solenoid 25 of relay ll, by conductor 26, to contact 21 of a double pole double throw switch 28, blade 29 of said switch, by conductor 30, back by switch 20, to source IS.

The secondary winding l3 of transformer II has one end of its winding grounded as indicated at 3| and its other end is connected by conductor 32 with gap 8 of pilot burner 2 through insulated connections therewith, as disclosed in my other cases referred to herein. When transformer II is energized as just described, the potential of its secondary is sufficient to jump the gap 8 in the event there is a flame issuing from the jet of the pilot burner but this potential is insufllcient to break the gap across air, in the absence of the pilot flame, and the transformer draws only a small current not enough to energize the operating solenoid 25 of relay I4; the circuit contacts of this relay thus remain open, and

other operating equipment remains in off position. Under these conditions, and whenever there is a failure of the pilot burner, the equipment being connected through switch 20 with a supply of power, a signal device 33, such as a bell, lamp, or the like is operated from said source. The circuit thereby provided for this signal appliance 33, is from switch 20, conductors 2|, 34, through signal device 33, thence conductor 35, upper contacts 36 of relay I5 which are closed by the movable contactor 31 thereof, and

To supply gas to and ignite the gas issuing from pilot burner 2, valve III must be energized to open and the potential supplied to gap 8 must be increased sufliciently to jump the air or unignited fuel space in the gap. To increase this potential, transformer II has its primary winding I2 provided with a tap 39 so that when the source of power is connected with the primary with the appropriate lesser number of turns, the secondary potential will be increased the required amount. In order todo this, the switch 28 is manually moved to the dotted line position until the pilot burner has been ignited. By this operation the current is supplied from switch by conductor H, to end 22, winding I2 through to tap 39, thence by conductor 40, contact of switch 28, blade 29 thereof, and conductor 30, back through switch 20 to the other side of the source, and at the same time a circuit from switch 20 is completed by conductors 2| and 42 through electrically operated valve I0, and back by conductor 43, blade 44 of switch 23, contact 45 thereof, and conductors '33 and 33, back to switch 20 and the other side of the source. In this way the fuel passage is opened to the pilot burner 2 and the ignition thereof is effected, but electrically operated valve9 remains closed since relays I4 and I5 are still open.

Upon ignition of the gas from the pilot burner, switch 28 is released so as to return to its normal position; the return of the switch'is so quick as not to interfere with the flow of gas to this burner by momentary closure of valve III which immediately opens upon closure of the switch 23' in its normal position under influence of spring 39. With the switch 28 in its normal position again the entire winding I2 of transformer II is connected with the source of current as previously set forth. The potential of secondary winding I3 is reduced but is suflicient to bridge the gap through the flame and thereby the primary winding I2 draws an increased amount of current, sufiicient through solenoid of relay I4 to effect a closing of its circuit contacts.

Closing of the circuit contacts of relay I4 closes the circuit from secondary winding I8 of transformer I6, by conductor 46, closed circuit contacts ofrelay I4, conductor 41, through solenoid 48 of relay I5, back by conductor 49 to the other end of winding I8. This energizes relay I5 drawing its movable contactor 31 to close the lower contacts 50 thereof. The circuits to both electrically operated valves I0 and 3 are thus closed, namely: from the source at switch 20, conductors 2| and 42 to valves I 0 and 8, thence from valve III, through conductor 43, blade of switch 28, contact 5| thereof, to conductor 52, and from valve 9 by conductor 83 directly to conductor 52, thence for both valve operating windings through lower contacts 50 closed by contactor 31, and conductors 33 and 30, .to switch' 20, to the other side' of the source. Energizing 2,238,896 valve I0 maintains the proper supply of gas to pilot burner 2 and the energizing of valve 9 supplies gas to main burner I subject to its control by the usual operation of valve 6. As a means for fixing the potential relationship of the secondary winding I8 of transformer I6, a conductor 54 may be connected from one end of this secondary I8 to one end of the primary I2 of transformer II as indicated at 22 which may preferably be connected with the grounded side of the source of electric current supply.

After ignition of the pilot burner flame and return of switch 28 to its normal position as just set forth, the control system is operating under normal conditions. The valves 9 and II) will remain in their open positions until the flame of the pilot burner is removed from the gap 8. Should this occur, the current in relay I4 will be reduced to such a point that it will drop out, thus opening relay I5 and thereby causing both gas valves to close, and effect the actuation of the signal device 33. Another condition, if it should occur, will also cause the gas valvesto close; if a short circuit of the secondary I3 of transformer II, or of the gap 8, or of the conductors leading to the gap, should' occur it would result in the short circuiting of the primary I! of transformer I6, thereby reducing its secondary voltage to zero or to such an extent that relay I5 would drop out, resulting in the closing of the fuel valves.

This last condition is important as a safety measure in the operation of the system since without such a feature an accumulation of soot in the pilot burner or a ground of the high tension cable supplying the burner would cause the relay to remain closed and fuel valves open even if the pilot were not lighted.

Having described a highly satisfactory arrangement of my invention, I do not wish to limit myself to any of the specific arrangement details for the purpose of giving an example or illustration of employment of the invention for it will be obvious that wide departure from the above may be made without departing from the spirit and scope of my invention, which is as set forth in the following claims.

I claim:

1. A safety control and ignition system for fuel burners, including a burner with a spark gap bridging the flame space projecting from a fuel jet of the burner, a transformer having a primary winding, and a high potential secondary connected with said spark gap of the burner, a source of alternating current supply, means normally connecting said source of current supply with said primary winding of the transformer so as to produce a potential in the secondary winding suflicient only to produce a passage of sparks across the gap when a flame is present therein but operable to connect a lesser number of turns of the transformer primary winding with the source of current supply to increase the secondary potential for fuel ignition, means dependent upon the current consumption of the transformer for controlling the supply of fuel to the burner, and means for shutting ofi the supply of fuel to the burner in the event of excessive current flow from the secondary winding of the transformer.

2. A safety control and ignition system for fuel burners, including a burner with a spark gap bridging the flame space projecting from a fuel jet of the burner, a transformer having a primary winding, and a high potential secondary connected with said spark gap of the burner, a

I poses or a lower potential only suificient to prosource of alternating current supply, means normally connecting said source of current supply with said primary winding of the transformer so as to produce a potential in the secondary winding sufficient only to produce a passage of sparks across the gap when a flame is present therein but operable to connect a lesser number of turns of the transformer primary winding with the source of current supply to increase the secondary potential for fuel ignition, means dependent upon the current consumption of the transformer for controlling the supply of fuel to the burner, means for shutting off the supply of fuel to the burner in the event of excessive current flow from the secondary winding of the transformer, said means including a second transformer excited from the secondary winding of said first transformer, and a relay operable by said second transformer only during the normal operation of the first transformer in passing sparks through a flame in the spark gap.

3. A safety control and ignition system for fuel burners, including a burner with a spark gap bridging the flame space projecting from a fuel jet of the burner, a transformer having a primary winding, and a high potential secondary connected with said spark gap of the burner, a source of alternating current supply, means for connecting said source of current supply with said primary winding of the transformer so as to produce a potential in the secondary windingsuflicient to produce a passage of sparks across the gap for ignition purposes or a lower potential only sufficient to produce a passage of sparks across the gap when a flame is present therein, a relay connected with the primary winding of the transformer and dependent for its operation upon the current passing therethrough when the secondary winding is producing a potential which produces a passage of sparks through a flame from the burner, a second relay dependent upon the potential supplied to the spark gap and upon the operation of said first relay, electrically operated valves for the fuel burners, and means for connecting said electrically operated valves with the source of current supply dependent upon the operation of said two relays for actuating the valves to their open position.

4. A safety control and ignition system for fuel burners, including a burner with a spark gap bridging the flame space projecting from a fuel jet of the burner, a transformer having a primary winding, and a high potential secondary connected with said spark gap of the burner, a source of alternating current supply, means for connecting said source of current supply with said primary winding of the transformer so as to produce a potential in the secondary sufficient to produce a passage of sparks across the gap for ignition purduce a passage of sparks across the gap when a flame is present therein, a relay connected with the primary winding of the transformer and dependent for its operation upon the current passing therethrough when the secondary winding is producing a potential which produces a passage of sparks through a flame from the burner, a second relay dependent upon the potential supplied to the spark gap and upon the operation of said first relay, electrically operated valves for the fuel burners, means for connecting said electrically operated valves with the source of current supply dependent upon the operation of said two relays for actuating the valves tc their open position, and means for shifting the connections of the source of current supply with the primary winding of said transformer for effecting ignition of fuel from the burner and simultaneously connecting the electrically operated valve for the burner having the spark gap with the source of current supply independent of said relays until the fuel has been ignited.

5. A safety control and ignition system for fuel burners, including a burner with a spark gap bridging the flame space projecting from a fuel jet of the burner, a transformer having a primary winding, and a high potential secondary connected with said spark gap of the burner, a source of alternating current supply, means for connecting said source of current supply withsaid primary winding of the transformer so as to produce a potential in the secondary winding sufficient to produce a passage of sparks across the gap for ignition purposes or a lower potential only suflicient to produce a passage of sparks across the gap when a flame is present therein, a relay connected with the primary winding of the transformer and dependent for its operation upon the current passing therethrough when the secondary winding is producing a potential which produces a passage of sparks through a flame from the burner, a second relay dependent upon the potential supplied to the spark gap and upon the operation of said first relay, electrically operated valves for the fuel burners, means for connecting said electrically operated valves with the source of current supply dependent upon the operation of said two relays for actuating the valves to their open position, and means for shifting the connections of the source of current supply with the primary windingof said transformer for effecting ignition of fuel from the burner and simultaneously connecting the electrically operated valve for the burner having the spark gap with the source of current supply independent of said relays until the fuel has been ignited, a signal device, and means for connecting said signal device with the source of current supply whenever either of said relays is' deen'erglzed.

JAMES E. CLARK. 

